Conventionally, in the manufacture of semiconductor devices, micro-processing by lithography using a photoresist composition has been carried out. The micro-processing is a processing method comprising forming a thin film of a photoresist composition on a substrate to be processed, such as a silicon wafer or the like, irradiating actinic rays such as ultraviolet rays through a mask pattern on which a pattern for a semiconductor device is depicted, developing it to obtain a photoresist pattern, and etching the substrate to be processed, such as a silicon wafer or the like by use of the photoresist pattern as a protective film. However, in recent progress in high integration of semiconductor devices, there has been a tendency that shorter wavelength actinic rays are being used, i.e., ArF excimer laser beam (193 nm) has been taking the place of KrF excimer laser beam (248 nm). Along with this change, influences of random reflection and standing wave of actinic rays from a substrate have become serious problems. Accordingly, it has been widely studied to provide an anti-reflective coating between the photoresist and the substrate to be processed (Bottom Anti-Reflective Coating, BARC).
As the anti-reflective coating, inorganic anti-reflective coatings made of titanium, titanium dioxide, titanium nitride, chromium oxide, carbon or a-silicon, etc., and organic anti-reflective coatings made of a light absorbing substance and a high molecular compound are known. The former requires an installation such as a vacuum deposition apparatus, a CVD (chemical vapor deposition) apparatus or a sputtering apparatus, etc. In contrast, the latter is considered advantageous in that it requires no special installation so that many studies have been made. For example, mention may be made of a novolak resin type anti-reflective coating and an acrylic resin type anti-reflective coating which have a hydroxyl group being a crosslinking reaction group and a light absorbing group in the same molecule (see, for example Patent Documents 1 and 2).
A pattern forming method is disclosed, in which a resist underlayer coating material is improved in etching resistance in substrate processing by using a polymer containing a styrene derivative or a vinylnaphthalene derivative for a resist underlayer coating (see, for example Patent Document 3).
The physical properties desired for organic anti-reflective coating materials include high absorbance to light and radioactive rays, no intermixing with a layer applied on the anti-reflective coating (being insoluble in a solvent used for materials applied on the anti-reflective coating), no diffusion of low molecular substances from the anti-reflective coating materials into the topcoat resist on applying or drying with heat, and a higher dry etching rate than the photoresist (see, for example, Non-patent Documents 1, 2 and 3).
When miniaturization of resist pattern progresses in future, problems such as a low resolution and collapse of resist pattern after development occur, and thus it is desired to make photoresists thinner. Therefore, it is difficult to obtain a film thickness of resist pattern sufficient for the processing of substrates, and processes for providing a function as a mask in the substrate processing not only for resist pattern but also for coating-type underlayer coating formed between a resist and a semiconductor substrate to be processed become required. As the coating-type underlayer coating for such a process, a coating-type underlayer coating for lithography having a selection ratio of dry etching rate close to that of photoresists, a coating-type underlayer coating for lithography having a lower selection ratio of dry etching rate than that of photoresists, or a coating-type underlayer coating for lithography having a lower selection ratio of dry etching rate than that of semiconductor substrates, which is different from conventional high etch rate coating-type underlayers, becomes required. It is also able to confer anti-reflective performance to the coating-type underlayer coatings, and they can have the function of the conventional anti-reflective coatings together.
On the other hand, for obtaining fine resist pattern, it begins to use a process in which the resist pattern and the coating-type underlayer coating are made thinner on dry etching of coating-type underlayer coating than the width of pattern on the development of photoresists. As the coating-type underlayer coating for such a process, a coating-type underlayer coating having a selection ratio of dry etching rate close to that of photoresists which is different from conventional high etch rate anti-reflective coatings, becomes required. It is also able to confer anti-reflective performance to the coating-type underlayer coatings, and they can have the function of the conventional anti-reflective coatings together.    Patent Document 1: U.S. Pat. No. 5,919,599    Patent Document 2: U.S. Pat. No. 5,693,691    Patent Document 3: JP-A 2004-271838    Non-patent Document 1: Tom Lynch et al., “Properties and Performance of Near UV Reflectivity Control Layers”, US, in Advances in Resist Technology and Processing XI, Omkaram Nalamasu ed., Proceedings of SPIE, 1994, Vol. 2195, p. 225-229    Non-patent Document 2: G. Taylor et al., “Methacrylate Resist and Antireflective Coatings for 193 nm Lithography”, US, in Microlithography 1999: in Advances in Resist Technology and Processing XVI, Will Conley ed., Proceedings of SPIE, 1999, Vol. 3678, p. 174-185    Non-patent Document 3: Jim D. Meador et al., “Recent Progress in 193 nm Antireflective Coatings, US, in Microlithography 1999: in Advances in Resist Technology and Processing XVI, Will Conley ed., Proceedings of SPIE, 1999, Vol. 3678, p. 800-809